G1 callback arguments (ARRAY ref).
The g1 callback is called like: &$g1Callback(@{$g1CallbackArgs},
\$rc,
$ruleId,
$value,
$index,
$lhs,
@rhs),
where $value is the AST parse tree value of RHS No $index of this G1 rule number $ruleId,
whose full definition is $lhs ::= @rhs.
If the callback is defined,
this will always be executed first,
and it must return a true value putting its eventual result in $rc.
Only when it returns true,
lexemes are processed.

Lexeme callback arguments (ARRAY ref).
The lexeme callback is called like: &$lexemeCallback(@{$lexemeCallbackArgs},
\$rc,
$name,
$ruleId,
$value,
$index,
$lhs,
@rhs),
where $value is the AST parse tree value of RHS No $index of this G1 rule number $ruleId,
whose full definition is $lhs ::= @rhs.
The RHS being a lexeme,
$name contains the lexeme's name.
If the callback is defined,
this will always be executed first,
and it must return a true value putting its result in $rc,
otherwise default behaviour applies: return the lexeme value as-is.